It came as the government announced its decision to award the franchise to Abellio, owned by the Dutch national rail operator, until 2025.
Abellio has pledged to invest £1.4bn to improve services in the east of England, including between London Liverpool Street and Norwich, Stansted Airport and Cambridge.
Canadian-based Bombardier, which has its main UK centre in Derby, has won a £1bn contract to supply 660 carriages in a move that will secure 1,000 jobs for a decade.
Abellio East Anglia, rebranded from current franchise-holder Abellio Greater Anglia, will start the new franchise in October.
Abellio has pledged to bring more than 1,040 new carriages into service, and introduce faster journey times and free wi-fi for all users.
Transport secretary Chris Grayling said: "We are making the biggest investment in the railways since the Victorian era.
"By awarding this franchise to Abellio East Anglia we will improve journeys for people in East Anglia.
"Abellio's decision will ensure our train-building industry in Derby remains strong.
"This is part of our plan to make an economy that works for everyone - not just the privileged few - by ensuring prosperity is spread throughout the country."
Abellio has pledged to deliver at least four 90-minute services - two in each direction - between London and Norwich each weekday and two 60-minute services a day between London and Ipswich.
By 2021, there will be more than 32,000 more seats on services arriving at London Liverpool Street in the morning peak, while the new franchise will introduce 1,144 additional weekday services- an increase of 13% - to stations including Cambridge, Norwich, Stansted Airport, Lowestoft, Southend and London Liverpool Street.
Dominic Booth managing director of Abellio UK, said: "This is great news not only for Abellio but for the whole of East Anglia.
"We are pleased to become preferred bidder to deliver a transformation in rail services across the region.
"It will enable us to build on the successes of the two short East Anglian franchises we have run since 2012, and we commend the DfT (Department for Transport) in running a transparent and rigorous procurement process."
Des McKeon, UK commercial director at Bombardier Transportation, said: "We're delighted to be chosen, pending final contract signing, as the preferred supplier for new trains for the East Anglia franchise.
"We look forward to working with our customer, Abellio UK, to support them in transforming rail services throughout the region and delivering an enhanced customer experience through the provision of new trains."
The government's decision was greeted with criticism on social media from passengers unhappy with the current service provided by Abellio Greater Anglia.
Anthony Smith, chief executive of the watchdog group Transport Focus, said: "Abellio will need to work hard during this new franchise to deliver on its bold promises.
"Passengers will welcome the much-needed new trains, automatic delay compensation and the strong emphasis on punctuality.
"Part-time commuters will keenly await the introduction of new types of tickets next autumn."
He added that, in a previous Transport Focus survey, 77% of Abellio's passengers were satisfied overall with their service, with only 36% satisfied with value for money.
"We'll be watching closely to see how this ambitious plan is delivered," he said.
Unite union national officer for the rail industry Tony Murphy said: "This is excellent news for the workers at Bombardier and this vote of confidence by Abellio East Anglia is a testament to their dedication, expertise and hard work.
"It is also good for the wider local economy and the supply chain.
"This boost for industrial production in the East Midlands shows that, despite the challenges posed by the Brexit vote, the UK manufacturing sector is open for business and remains amongst the global leaders for high-quality engineering."
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